Kinetics and mechanisms of nucleophilic displacements with heterocycles as leaving groups. 2. N-benzylpyridinium cations: rate variation with steric effects in the leaving group
The c-alkylation of nitroalkame anions by l-substituted-2--butyl-4-phenyl- and -2,4-diphenyl-5,6-dihydrobenzo(ulbarh]quinolinium cations
作者:Alan R. Katritzky、M. Akram Kashmiri、Dieter K. Wittmann
DOI:10.1016/s0040-4020(01)91797-1
日期:1984.1
- The N-substituents are transferred from the title cations to the C-atom of nitroalkane anions in highyield at 25-80°C in DMSO solution. The title cations are readily available from the appropriate pyrylium cations and primary amines of types RCH2,NH2, and RR'CHNH2, allowing a general 2-step method for the preparation of higher nitro- alkanes. Spectral properties of a variety of nitroalkanes are
Kinetics and mechanisms of nucleophilic displacements with heterocycles as leaving groups. Part 8. Conductimetric and spectrophotometric rate constants for the reactions of pyridinium and related cations with piperidine in chlorobenzene
作者:Alan R. Katritzky、Yu Xiang Ou、Joan Ellison、Giuseppe Musumarra
DOI:10.1039/p29830001421
日期:——
which the spectrophotometric method fails. It gives equivalent results. NN′-Dimethylthiourea displaces heterocyclic leavinggroups at rates similar to those for piperidine. Compared with α-hydrogen, α-methyl groups render pyridine a less effective leavinggroup, whereas α-ethoxycarbonyl groups show a large rate enhancement.
Identification of the products of solvolysis of N-benzylpyridinium cations in the absence of nucleophiles
作者:Alan R. Katritzky、Charles M. Marson、Jen-Luan Chen、Franciszek Saczewski、Roy W. King
DOI:10.1039/p29860001331
日期:——
and penta-cyclic N-benzylpyridinium tetrafluoroborates undergo thermolysis in chlorobenzene as solvent to give products of benzylation both of the solvent and of the pyridine leaving group. Thermolysis alone, and in nitrobenzene as solvent, yielded mainly products of benzylation of the leaving group. The results support the previously postulated mechanism of unimolecular solvolysis of compounds of these
Kinetics and mechanisms of nucleophilic displacements with heterocycles as leaving groups. Part 6. Reactions of N-(substituted benzyl)azaheterocyclonium compounds with piperidine
作者:Alan R. Katritzky、Wlodzimierz H. Basinski、Yu Xiang Ou、Giuseppe Musumarra、Ranjan C. Patel
DOI:10.1039/p29820001055
日期:——
The preparation is described of series of N-(p-substituted)benzyl and N-(2-furfuryl) compounds with different heterocyclic leaving groups. First- and second-order rate constants for their reactions with piperidine in chlorobenzene are measured and discussed. Plots of k2 values for substituted compounds versus k2 for the parent N-benzyl derivative are linear for each substituent despite variable temperature